He's using a MOPAR reluctor and pickup coil adapted to the GM 6-cylinder distributor cam. Good-looking installation, but there's a reason the GM HEI cap is so big. There's a danger of flashover from one cap terminal to another, especially if an open-circuited plug wire is present, or a wire falls off a plug. Don't run a wide plug gap if you choose to use the original cap and rotor with HEI system coil voltage.
Jerry
